Package of freeze Storage Container and Process for Producing the Same

ABSTRACT

It is demanded that packages for cryopreservation containers which can prevent the conventional cryopreservation containers stored at very low temperatures, namely −80 to −196° C., from being damaged and are excellent in heat sealability be developed. The present invention provides a package for a cryopreservation container comprising at least an adhesive fluoropolymer film. The package for a cryopreservation container according to the invention makes it possible to store blood, rare cells and vital tissues in a very low temperature environment without any damage to the container. Further, the sealing strength resulting from heat sealing after placing a cryopreservation container in the packages is very good and, therefore, liquid nitrogen can be inhibited from entering the inside and thus contamination with bacteria, viruses or the like contained in liquid nitrogen can be avoided and the package can be prevented from being broken by expansion of intruder liquid nitrogen on the occasion of thawing.

TECHNICAL FIELD

The present invention relates to a package for a cryopreservationcontainer and a method of producing the same. More particularly, itrelates to a package for a cryopreservation container which comprises alaminate film and is used for packaging a cryopreservation container andin which the laminated film comprises a low-temperature resistant resinfilm and an adhesive fluoropolymer film, with the adhesive fluoropolymerfilm being disposed at least on one outermost layer.

BACKGROUND ART

Blood, rare cells and vital tissues are generally stored at very lowtemperatures, namely at about −80 to −196° C. In particular, bone marrowcells, hematopoietic stem cells and like rare cells are effectively usedin the treatment of intractable diseases such as leukemia, and atechnology of storing them for a long period of time has been demanded.For the storage at such very low temperatures, blood, rare cells andvital tissues are generally stored in tightly closed containers thereforimmersed mainly in liquid nitrogen.

As for the cryopreservation containers for such storage, vials made ofpolypropylene, for instance, are commercially available for use on thelaboratory level; they are inexpensive and convenient from the handlingviewpoint.

With the recent development of cord blood banks, bag-like containersexcellent in low-temperature resistance and flexibility have beenproposed. For example, containers made of a laminated film composed of apolyimide film and fluorinated ethylene-propylene polymer film (PatentDocument 1) and containers made of a tetrafluoroethylene-ethylenecopolymer film (Patent Document 2) have been proposed. Further, PatentDocument 3 discloses cryopreservation containers molded from an electronbeam-irradiated, biaxially stretched ethylene-vinyl acetate copolymerfilm. Patent Document 4 discloses cryopreservation containers moldedfrom a biaxially stretched, crosslinked polyethylene film.

On the other hand, the present inventors developed cryopreservationcontainers which are constituted of a laminated film consisting of anultrahigh molecular weight polyethylene layer and a thermoplastic resinlayer compatible with the ultrahigh molecular weight polyethylene layerand are superior to the cryopreservation containers disclosed in PatentDocuments 1 to 4, and applied for a patent for the same (Patent Document5).

When blood, rare cells and vital tissues are preserved in thecryopreservation containers mentioned above in liquid nitrogen, thecryopreservation containers are further packaged so that the contentsmay be protected in case of damage of the containers and liquid nitrogenmay be prevented from entering the cryopreservation containers. Forpackaging them, packages made of a perfluoroethylene-propene copolymer,among others, are generally used.

However, such packages are fluororesin-made ones and therefore themolding or processing for manufacturing them must be carried out atelevated temperatures. In spite of this, their heat seal strength is notso high but the sealed portions are possibly in danger of peeling away.After packaging of a cryopreservation container in a package, the mouthportion of the package is heat sealed for tight closure. This mouthportion is also susceptible to peeling and there is the possibility thatliquid nitrogen may enter the inside. This work is carried out inmedical institutions such as cord blood banks and heat sealing undersevere conditions is a burden on workers. Further, when polypropylenevials for cryopreservation or cryopreservation containers described inPatent Documents 1 to 4 are packaged, there is the possibility that whenthe packages are damaged and liquid nitrogen enters the inside, thecryopreservation containers may also be damaged.

Ultrahigh molecular weight polyethylene films are formed by cuttingprocessing and are relatively thick. When they are used as materials forpackages, the conduction of heat to the contents may possibly beaffected.

Known as materials for packages for cryopreservation containers arepolytetrafluoroethylene, polychlorotrifluoroethylene,tetrafluoroethylene/hexafluoropropylene copolymers,tetrafluoroethylene/ethylene copolymers and polyimides, among others(cf. e.g. Patent Document 6 and Patent Document 7). However, thosefluororesins which are used in preparing the conventional packagesrequire elevated temperatures for sealing and their sealability isinsufficient in some cases.

Patent Document 1: Japanese Patent Publication S49-008079 PatentDocument 2: Utility Model Publication S55-055069 Patent Document 3:Japanese Patent Publication S55-044977 Patent Document 4: JapanesePatent Publication S62-057351 Patent Document 5: Japanese KokaiPublication H08-173505 Patent Document 6: Japanese Kokai PublicationH11-139459 Patent Document 7: Japanese Kokai Publication 2003-267471DISCLOSURE OF INVENTION Problems which the Invention is to Solve

Therefore, it is demanded that packages for cryopreservation containerswhich can prevent the conventional cryopreservation containers stored atvery low temperatures, namely −80 to −196° C., from being damaged andare excellent in heat sealability be developed.

Means for Solving the Problems

The present inventors proposed using an adhesive fluoropolymer film fora package for a cryopreservation container.

The present invention relates to:

(1) a package for a cryopreservation container comprising at least anadhesive fluoropolymer film;(2) the package for a cryopreservation container according to (1),wherein the adhesive fluoropolymer film is made of an adhesivefluoropolymer containing at least one adhesive site;(3) the package for a cryopreservation container according to (2),wherein the at least one adhesive site is selected from the groupconsisting of carbon-carbon double bond, carbonyl group [—C(═O)],carbonyl group-containing groups or bonds, hydroxyl group, cyano group,sulfonic acid group and epoxy group;(4) the package for a cryopreservation container according to (3),wherein the adhesive fluoropolymer contains at least one reactivefunctional group as the adhesive site and is a copolymer obtained bycopolymerizing the following monomers (A) and (B):(A) a fluorinated monomer containing no reactive functional group;(B) a fluorinated monomer containing the at least one reactivefunctional group.(5) the package for a cryopreservation container according to (4),wherein the fluorinated monomer containing no reactive functional groupis represented by the formula (1) given below:

(wherein X¹ and X² each is hydrogen atom or halogen atom and Y ishydrogen atom, fluorine atom, a fluorinated alkyl group containing 1 to5 carbon atoms or a fluorinated oxyalkyl group containing 1 to 5 carbonatoms);(6) the package for a cryopreservation container according to (5),wherein the fluorinated monomer containing no reactive functional groupcomprises at least one monomer selected from the group consisting oftetrafluoroethylene, vinylidene fluoride, 1,2-difluorochloroethylene,hexafluoropropylene, perfluoro(vinyl methyl ether) and perfluoro(vinylpropyl ether);(7) the package for a cryopreservation container according to (4) to(6), wherein the fluorinated monomer containing the at least onereactive functional group is represented by the formula (2) given below:

(wherein X¹ and X² each is hydrogen atom or halogen atom, Z is hydroxylgroup, carboxyl group, cyano group, sulfonic acid group or epoxy groupand R_(f) is a fluorinated alkylene group containing 1 to 40 carbonatoms, a fluorinated oxyalkylene group containing 1 to 40 carbon atomsor a fluorinated alkylene group containing 1 to 40 carbon atoms and atleast one ether bond);(8) the package for a cryopreservation container according to (4),wherein the adhesive fluoropolymer is represented by the formula (3)given below:

(wherein X¹ and X² each is hydrogen atom or halogen atom, Y¹ and Y² eachis hydrogen atom, fluorine atom, a fluorinated alkyl group containing 1to 5 carbon atoms or a fluorinated alkoxy group containing 1 to 5 carbonatoms, Z is hydroxyl group, carboxyl group, cyano group, sulfonic acidgroup or epoxy group, R_(f) is a fluorinated alkylene group containing 1to 40 carbon atoms, a fluorinated oxyalkylene group containing 1 to 40carbon atoms or a fluorinated alkylene group containing 1 to 40 carbonatoms and at least one ether bond and the ratio (1+m)/n is 2 to 2000);(9) the package for a cryopreservation container according to (3),wherein the adhesive fluoropolymer comprises a fluorinatedmonomer-derived fluorinated monomer unit and a nonfluorinatedmonomer-derived nonfluorinated monomer unit;(10) the package for a cryopreservation container according to claim 9,wherein the fluorinated monomer is tetrafluoroethylene and thenonfluorinated monomer is ethylene;(11) the package for a cryopreservation container according to claim 1comprising the adhesive fluoropolymer film on at least one outermostlayer and a film other than the adhesive fluoropolymer film;(12) the package for a cryopreservation container according to (11),wherein the film other than the adhesive fluoropolymer film is alow-temperature resistant resin film;(13) the package for a cryopreservation container according to (12),wherein the low-temperature resistant resin comprises at least one resinselected from the group consisting of ultrahigh molecular weightpolyethylene, polyimides, polytetrafluoroethylene,ethylene-tetrafluoroethylene copolymers and ethylene-vinyl acetatecopolymers;(14) the package for a cryopreservation container according to (13),wherein the low-temperature resistant resin is a polyimide;(15) a method of producing a package for a cryopreservation containercomprising shaping an adhesive fluoropolymer film into a bag-likearticle by heat sealing; and(16) the method of producing a package for a cryopreservation containeraccording to (15), comprising shaping a laminated film comprising theadhesive fluoropolymer film on at least one outermost layer and a filmother than the adhesive fluoropolymer film, into a bag-like article byheat sealing.

EFFECTS OF THE INVENTION

The package for a cryopreservation container according to the inventionmakes it possible to store blood, rare cells and vital tissues in a verylow temperature environment without any damage to the container. Inparticular, even when it is used in combination with thosecryopreservation containers (e.g. cryopreservation containers describedin Patent Documents 1 to 4) which cannot always be said to be excellentin cryopreservation or polypropylene vials in use on the experimentlevel, the package can produce its effects. Since it is excellent inlow-temperature heat sealability, the production stability in packagemanufacture in a factory is improved and workers at working places wherebiological samples are stored can seal it with ease. Further, thesealing strength resulting from heat sealing after placing acryopreservation container in the packages is very good and, therefore,liquid nitrogen can be inhibited from entering the inside and thuscontamination with bacteria, viruses or the like contained in liquidnitrogen can be avoided and the package can be prevented from beingbroken by expansion of intruder liquid nitrogen on the occasion ofthawing.

BEST MODES FOR CARRYING OUT THE INVENTION

The package for a cryopreservation container according to the inventionis a bag-shaped package for packaging the cryopreservation container forthe purpose of protecting the contents of the cryopreservation containerin case of the same being damaged and for the purpose of preventingliquid nitrogen from entering the cryopreservation container and isconstituted of a film comprising at least an adhesive fluoropolymerlayer.

The adhesive fluoropolymer film is a film molded from a polymer whosemain chain and/or side chains contain at least one fluorine atom andthat film functions as a film adhering to a substrate or base made of anorganic material. The adhesion or adhering, so referred to herein, isthe binding of the adhesive fluoropolymer film to the organic materialvia physical and/or chemical bonds, among others. From the bond strengthviewpoint, chemical bonds are preferred although the bonds are notlimited thereto. The chemical bonds include covalent bonds, ionic bonds,coordination bonds, hydrogen bonds and intermolecular forces, amongothers. Preferred bonds from the bond strength viewpoint are, but arenot limited to, covalent bonds and ionic bonds. More preferred arecovalent bonds.

The organic material mentioned above includes general-purpose resinmoldings, such as films, tubes, synthetic fibers, synthetic rubbers andsolids, made of polyethylene, polycarbonates, polystyrene, polyvinylchloride, polyvinyl acetate, polyesters and low-temperature-resistantresins such as ultrahigh molecular weight polyethylene, polyimides,polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymers andethylene-vinyl acetate copolymers, and naturally occurring organicmatters such as natural rubbers, natural fibers, woods, papers andleathers and, further, adhesive fluoropolymers. Preferred ones amongthese from the viewpoint of improving the low-temperature resistance ofthe package itself are, but are not limited to, the adhesivefluoropolymer film itself and ones having a function enabling theiradhesion to the low-temperature-resistant resin film.

From the moldability/processability viewpoint, the adhesivefluoropolymer has a number average molecular weight of about 1,000 to1,000,000, preferably about 2,000 to 500,000, more preferably about5,000 to 300,000. These ranges have no restrictive meaning, however.

The adhesive fluoropolymer film can be produced by timely selecting aproper production method according to the molecular structure, glasstransition temperature and melting point, among others, of the adhesivefluoropolymer, as the one skilled in the art does. For example, theremay be mentioned compression molding, injection molding, extrusionmolding, T-die molding, inflation molding, solvent casting and so forth.A method preferred from the moldability/processability viewpoint is, butis not limited to, compression molding. Considering the conduction ofheat to the contents, the adhesive fluoropolymer film has a thickness ofabout 10 to 100 μm, preferably 10 to 50 μm, particularly preferably 10to 30 μm. These ranges have no restrictive meaning, however.

Preferred examples of the adhesive fluoropolymer are copolymers derivedfrom the following (A) and (B).

(A) A fluorinated monomer containing no reactive functional group.(B) A fluorinated monomer containing at least one reactive functionalgroup.

The reactive functional group, so referred to herein, is a functionalgroup capable of adhering to the organic material substrate mentionedabove via a covalent bond, ionic bond, coordination bond or hydrogenbond, for instance. For example, such functional group includes, but isnot limited to, hydroxyl group, carboxyl group, cyano group, sulfonicacid group, epoxy group and like groups. One preferred among these is,but is not limited to, the hydroxyl group which is readily activated byheat.

The fluorinated monomer mentioned above is one giving a copolymer whosemain chain and/or side chains contains at least one fluorine atomsubstituting for a hydrogen atom. It includes, for example, fluorinatedethylenic monomers, fluorinated ester monomers and fluorinated whollyaromatic monomers. Preferred ones are, but are not limited to,fluorinated ethylenic monomers in view of their ready availability andmoldability/processability of the copolymers obtained.

The copolymer mentioned above may be a binary one derived from at leastone (A) monomer and at least one (B) monomer by polymerization. Forexample, mention may be made of a binary one derived from one (A)monomer and one (B) monomer, a ternary one derived from two (A) monomersand one (B) monomer, and a ternary one derived from one (A) monomer andtwo (B) monomers. Preferred ones from the production cost viewpoint are,but are not limited to, binary or ternary ones.

As the copolymerization technique, there may be mentioned, among others,radical copolymerization, anion copolymerization, cationcopolymerization, emulsion copolymerization and plasma copolymerizationand an appropriate technique can be timely selected from among theseaccording to the monomer structure, polarity, solvent species and soforth, as the one skilled in the art does. A preferred one among themis, but is not limited to, radical copolymerization in view of the easeof production.

As for the constitution of the copolymer, there may be mentioned randomcopolymers, block copolymers, graft copolymers and alternatingcopolymers. Preferred ones are, but are not limited to, randomcopolymers from the ease of production viewpoint.

Further, the occurrence ratio (copolymerization ratio) between (A) and(B) in the above copolymer is, but is not limited to, 1 to 2000 of (A),preferably 100 to 2000 of (A), with (B) being taken as 1 in view of themoldability/processability of the copolymer.

The above-mentioned fluorinated monomer (A) containing no reactivefunctional group has none of the reactive functional groups enumeratedhereinabove and gives a copolymer whose main chain and/or side chainscontain at least one fluorine atom substituting for a hydrogen atom.Preferred ones are, but are not limited to, fluorinated ethylenicmonomers containing no reactive functional group in view of their readyavailability and of the moldability/processability of the copolymersobtained.

The fluorinated monomer (A) containing no reactive functional groupcontains at least one fluorine atom and, as examples thereof, there maybe mentioned monomers represented by the following formula (1).

(In the above formula, X¹ and X² each is hydrogen atom or halogen atomand Y is hydrogen atom, fluorine atom, a fluorinated alkyl groupcontaining 1 to 5 carbon atoms or a fluorinated oxyalkyl groupcontaining 1 to 5 carbon atoms.)

As the monomers represented by the above formula (1), there may bementioned, for example, tetrafluoroethylene, vinylidene fluoride,1,2-difluorochloroethylene, hexafluoropropylene, perfluoro(vinyl methylether) and perfluoro (vinyl propyl ether). Preferred aretetrafluoroethylene, vinylidene fluoride, 1,2-difluorochloroethylene andperfluoro (vinyl propyl ether) Preferred ones are, but are not limitedto, tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene andperfluoro (vinyl propyl ether) in view of their ready availability andof the moldability/processability of the copolymers obtained.

On the other hand, the fluorinated monomer (B) containing at least onereactive functional group contains at least one of the reactivefunctional groups enumerated hereinabove, and the copolymer obtained bypolymerization using the same contains at least one fluorine atomsubstituting for a hydrogen atom in the main chain and/or side chainsthereof. Preferred ones are, but are not limited to, fluorinatedethylenic monomers containing a reactive functional group or groups inview of their ready availability and of the moldability/processabilityof the copolymers obtained.

As examples of the fluorinated ethylenic monomer (B) containing at leastone reactive functional group, there may be mentioned monomersrepresented by the formula (2).

(In the above formula, X¹ and X² each is hydrogen atom or halogen atom,Z is hydroxyl group, carboxyl group, cyano group, sulfonic acid group orepoxy group and R_(f) is a fluorinated alkylene group containing 1 to 40carbon atoms, a fluorinated oxyalkylene group containing 1 to 40 carbonatoms or a fluorinated alkylene group containing 1 to 40 carbon atomsand at least one ether bond.)

As the monomers represented by the above formula (2), there may bementioned, for example, perfluoro(4-oxa-5-hexenol) (formula (4)),perfluoro(1,1-dihydro-6-heptenol) (formula (5)),perfluoro(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol) (formula (6)), perfluoro (4-oxa-5-hexenoic acid) (formula(7)), perfluoro(3,6-dioxa-4-trifluoromethyl-7-octenonitrile) (formula(8)), perfluoro(1,1,-dihydro-3-oxa-4-pentenesulfonic acid) (formula(9)), 1,2-epoxy-perfluoro(1,1,2-trihydro-6-pentene) (formula (10)) andlike monomers. Preferred ones are, but are not limited to, hydroxylgroup-containing ones such as perfluoro(4-oxa-5-hexenol) (formula (4)),perfluoro(1,1-dihydro-6-heptenol) (formula (5)) andperfluoro(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol) (formula (6)) in view of their giving copolymers excellentin low-temperature heat sealability.

Preferred constitutions of the adhesive fluoropolymer to be used in thepractice of the invention are, but are not limited to, copolymersrepresented by the formula (3) given below in view of the ease ofproduction thereof.

(In the above formula, X¹ and X² each is hydrogen atom or halogen atom,Y¹ and Y² each is hydrogen atom, fluorine atom, a fluorinated alkylgroup containing 1 to 5 carbon atoms or a fluorinated alkoxy groupcontaining 1 to 5 carbon atoms, Z is hydroxyl group, carboxyl group,cyano group, sulfonic acid group or epoxy group, R_(f) is a fluorinatedalkylene group containing 1 to 40 carbon atoms, a fluorinatedoxyalkylene group containing 1 to 40 carbon atoms or a fluorinatedalkylene group containing 1 to 40 carbon atoms and at least one etherbond and the ratio (1+m)/n is 2 to 2000.) When the ratio (1+m)/n is inexcess of 2000, there is the possibility that no sufficient adhesivenesscan be obtained any longer.

More preferred constitutions of the adhesive fluoropolymer to be used inthe practice of the invention are, but are not limited to, copolymersrepresented by the formula (11) given below in view of the ease ofproduction thereof and from the heat seal strength viewpoint.

(In the above formula, X¹ and X² each is hydrogen atom or halogen atom,Y¹ and Y² each is hydrogen atom, fluorine atom, a fluorinated alkylgroup containing 1 to 5 carbon atoms or a fluorinated alkoxy groupcontaining 1 to 5 carbon atoms, R_(f) is a fluorinated alkylene groupcontaining 1 to 40 carbon atoms, a fluorinated oxyalkylene groupcontaining 1 to 40 carbon atoms or a fluorinated alkylene groupcontaining 1 to 40 carbon atoms and at least one ether bond and theratio (1+m)/n is 2 to 2000.)

Particularly preferred constitutions of the adhesive fluoropolymer to beused in the practice of the invention are, but are not limited to,copolymers of tetrafluoroethylene and/or perfluoro(vinyl propyl ether)and perfluoro(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol) from the viewpoint of ready availability of the monomers,the ease of production and the heat seal strength. From the ease ofproduction viewpoint, the copolymer constituent ratio is a total ofabout 2 to 2000, preferably about 4 to 2000, tetrafluoroethylene monomerunits and/or perfluoro(vinyl propyl ether) monomer units perperfluoro(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol) monomer unit. The ranges given above have no restrictivemeaning, however.

In the practice of the invention, the adhesive fluororesin filmmentioned above is preferably one made of an adhesive fluoropolymercontaining at least one adhesive site.

The adhesive fluoropolymer may contain the above-mentioned reactivefunctional groups as the adhesive sites.

The adhesive fluororesin film may be one forming an adhesive fluororesinlayer to be described later herein. The adhesive fluoropolymer may beone constituting an adhesive fluororesin.

In the practice of the invention, the adhesive fluororesin layer is madeof the adhesive fluororesin.

The adhesive fluororesin, so referred to herein, is preferably onecomprising a fluoropolymer containing at least one adhesive site.

The fluoropolymer, so referred to herein, is a polymer containingfluorinated monomer units derived from a fluorinated monomer or monomersin the main chain thereof. The fluoropolymer may or may not containnonfluorinated monomer units derived from a nonfluorinated monomer ormonomers.

The term “monomer unit” as used herein referring to the fluoropolymer,means a monomer-derived portion constituting a part of the molecularstructure of the polymer. The tetrafluoroethylene unit, for instance, isrepresented by —(CF₂—CF₂)—.

The above-mentioned fluorinated monomer is not particularly restrictedbut may be any of fluorine atom-containing polymerizable compounds.Thus, for example, there may be mentioned tetrafluoroethylene [TFE],vinylidene fluoride [VdF], chlorotrifluoroethylene [CTFE], vinylfluoride [VF], hexafluoropropylene [HFP], hexafluoroisobutene,perfluoro(alkyl vinyl ether) [PAVE] species, and monomers represented bythe general formula (i):

CH₂═CX³(CF₂)_(n)X⁴  (i)

(wherein X³ represents hydrogen atom or fluorine atom, X⁴ representshydrogen atom, fluorine atom or chlorine atom and n represents aninteger of 1 to 10).

The above-mentioned nonfluorinated monomer is not particularlyrestricted but may be any of compounds containing no fluorine atom andcopolymerizable with the fluorinated monomers mentioned above. Forexample, there may be mentioned ethylene [Et], propylene, 1-butene,2-butene, vinyl chloride and vinylidene chloride.

As the above fluoropolymer, there may be mentioned the copolymers (I)and copolymers (II) mentioned below.

(I) Copolymers resulting from polymerization of at least TFE and Et;(II) Copolymers resulting from polymerization of at least TFE and atleast one monomer represented by the general formula (ii):

CF₂═CF-R_(f) ²  (ii)

(wherein R_(f) ² represents —CF₃ or —OR_(f) ¹ in which R_(f) ¹represents a perfluoroalkyl group containing 1 to 5 carbon atoms).

As the copolymers (I), there may be mentioned, for example, copolymersconstituted of at least 20 to 80 mole percent of TFE units and 80 to 20mole percent of Et units.

In the present specification, the mole percent values for the respectivemonomer units are the percentages of the numbers of moles of therespective monomers now constituting the respective monomer units in thecopolymer relative to that 100 mole percent which corresponds to thetotal number of moles of all the monomers now constituting the monomerunits constituting the molecular chain of the copolymer minus the numberof moles of the monomer from which the adhesive site-containing monomerunits to be mentioned later herein are derived.

The mole percent values given for the respective monomer units are thevalues determined from a ¹⁹F-NMR chart.

The copolymers (I) may contain, in the main chain thereof, other monomerunits derived from at least one other copolymerizable monomer inaddition to TFE units and Et units, and an appropriate monomer speciescan be selected as the other monomer according to the intended use ofthe laminate film to be obtained and can be subjected tocopolymerization.

As the other monomer, there may be mentioned HFP, CTFE, propylene,monomers represented by the general formula (iii):

CX⁵ ₂═CX⁶(CF₂)_(n)X⁷  (iii)

(wherein X⁵ and X⁶ are the same or different and each representshydrogen atom or fluorine atom, X⁷ represents hydrogen atom, fluorineatom or chloride atom and n represents an integer of 1 to 10), andmonomers represented by the general formula (iv):

CF₂═CF—OR_(f) ¹  (iv)

(wherein R_(f) ¹ represents a perfluoroalkyl group containing 1 to 5carbon atoms), among others. Generally, one or two of these are used.

The other monomer units may amount to 0 to 20 mole percent relative to100 mole percent of the monomer units constituting the molecular chainof each copolymer (I).

Preferred as the above fluoropolymer are the copolymers (I) since theyare excellent in thermal stability, chemical resistance, weatherresistance, electric insulation properties, low liquid chemicalpermeability and nonstickiness, among others, and Et/TFE/HFP copolymersare more preferred since they are excellent in thermal stability,chemical resistance, weather resistance, electric insulation properties,low liquid chemical permeability, nonstickiness, low-temperatureprocessability and transparency, among others. The HFP unit content inthe Et/TFE/HFP copolymers is preferably 5 to 20 mole percent, a morepreferred lower limit is 8 mole percent and a more preferred upper limitis 17 mole percent. The Et/TFE/HFP copolymers may contain, in additionto Et-, TFE- and HFP-derived units, units derived from one or more ofthe above-mentioned other monomer species other than HFP units withinthe limits within which the favorable properties of the Et/TFE/HFPcopolymers will not be impaired.

In the present specification, the term “adhesive site” means afunctional group showing affinity for or reactivity with theabove-mentioned organic materials such as polyimide [PI] films.

In the present specification, the term “affinity” means the ability toshow such an interaction with the organic materials such as PI filmswithout modifying the chemical structure as hydrogen bonding or van derWaals force and the term “reactivity” means the ability to modify thechemical structure of the functional group, for instance.

The adhesive sites are generally possessed by the above-mentionedfluoropolymer in the main chain or side chains thereof.

The adhesive sites are not particularly restricted but include, amongothers, carbon-carbon double bonds, carbonyl group [—C(═O)], carbonylgroup-containing groups or bonds. In the fluoropolymer containing suchan adhesive site, the adhesive sites may be of a kind or there may betwo or more kinds of adhesive sites.

The above-mentioned reactive functional groups may also serve as the“adhesive sites”.

As the carbonyl group-containing groups or bonds mentioned above, theremay be mentioned, for example, the carbonate group, haloformyl group,formyl group, carboxyl group, carbonyloxy group [—C(═O)O—], acidanhydride group [—C(═O)O—C(═O)—], isocyanato group, amide group[—C(═O)—NH—], imide group [—C(═O)—NH—C(═O)—], urethane bond[—NH—C(═O)O—], carbamoyl group [NH₂—C(═O)—], carbamoyloxy group[NH₂—C(═O)O—], ureido group [NH₂—C(═O)—NH—] and oxamoyl group[NH₂—C(═O)—C(═O)—].

Preferred as the carbonyl group-containing groups or bonds are carbonategroups and haloformyl groups, among others, in view of the ease ofintroduction thereof and their high reactivity.

The above-mentioned carbonate group is a group having bonds representedby [—OC(═O)O—] and is represented by —OC(═O)O—R (in which R representsan organic group or a group IA atom, group IIA atom or group VIIB atom).As the organic group R in the above formula, there may be mentioned, forexample, alkyl groups containing 1 to 20 carbon atoms and alkyl groupscontaining 2 to 20 carbon atoms and containing at least one oxygen atomconstituting an ether bond, preferably alkyl groups containing 1 to 8carbon atoms and alkyl groups containing 2 to 4 carbon atoms andcontaining an oxygen atom constituting an ether bond, among others. Asthe above carbonate group, there may be mentioned, for example,—OC(═O)O—CH₃, —OC(═O)O—C₃H₇, —OC(═O)O—C₈H₁₇ and —OC(═O)O—CH₂CH₂OCH₂CH₃.

The above-mentioned haloformyl group is represented by —COY (in which Yrepresents a group VIIB atom), and —COF and —COCl, among others, arepreferred.

The number of the adhesive sites can be properly selected according tosuch factors as substrate species, shape, use and required bond strengthand according to the fluoropolymer species mentioned above. Generally,it is 3 to 1000 per 1×10⁶ carbon atoms in the main chain. When thenumber of carbonyl groups is counted, the number of the adhesive sitesis generally not less than 150, preferably not less than 250, morepreferably not less than 300, per 1×10⁶ main chain carbon atoms.

In the present specification, the number of the above-mentioned“adhesive sites” is determined by carrying out infrared absorptionspectrometry according to the method of determining the number ofcarbonyl group-containing functional group as described in InternationalPublication WO 99/45044.

As the above-mentioned adhesive fluororesin, there may be mentioned, forexample, those fluorine-containing ethylenic polymers containingcarbonyl group-containing functional groups which are described inInternational Publication WO 99/45044.

The above adhesive fluororesins can be obtained by introducing adhesivesites on the occasion of fluoropolymer production by polymerization andthe method of introducing adhesive sites is not particularly restrictedbut includes, for example, (1) the method comprising subjecting anadhesive site-containing monomer to copolymerization, (2) the methodcomprising carrying out the polymerization in an aqueous medium in themanner of emulsion polymerization, for instance, in the presence of anadhesive site-containing polymerization initiator to thereby introducethe polymerization initiator-derived adhesive site at one or eachpolymer chain terminus, and (3) the method comprising heating, forinstance, the polymer on the occasion of polymerization or afterpolymerization to convert carbon-carbon single bonds in the polymerchain to double bonds to thereby provide the polymer with adhesivesites.

The method (1) mentioned above can be carried out, for example, bycopolymerizing an adhesive site-containing monomer with fluorinatedmonomer species and composition selected according to the desiredadhesive fluororesin, if desired together with a nonfluorinated monomerin the conventional manner known in the art.

The method of the above copolymerization is not particularly restrictedbut may comprise, for example, random copolymerization, which is carriedout by introducing the adhesive site-containing monomer into the systemon the occasion of polymer chain formation by other comonomers such asthe fluorinated monomers, block copolymerization, or graftcopolymerization. In the case of graft copolymerization, there may bementioned, for example, the method comprising causing addition of anunsaturated carboxylic acid, which is to be mentioned later herein, tothe fluoropolymer.

The “adhesive site-containing monomer” mentioned above means an adhesivesite-containing polymerizable monomer which may contain one or morefluorine atoms or no fluorine atoms.

In the present specification, the “fluorinated monomers” and“nonfluorinated monomers” mentioned above have no such adhesive site asmentioned above.

When the adhesive site is a carbonyl group-containing group or bond, theadhesive site-containing monomer includes, among others,fluorine-containing monomers such as perfluoroacrylic acid fluoride,1-fluoroacrylic acid fluoride, acrylic acid fluoride,1-trifluoromethacrylic acid fluoride and perfluorobutenoic acid; andfluorine-free monomers such as acrylic acid, methacrylic acid, acrylicacid chloride and vinylene carbonate.

As the adhesive site-containing monomer, there may further be mentionedunsaturated carboxylic acids.

The unsaturated carboxylic acid, so referred to herein, any compoundcontaining at least one carbon-carbon unsaturated bond (hereinafter alsoreferred to as “copolymerizable carbon-carbon unsaturated bond”)enabling copolymerization and containing at least one carbonyloxy group[—C(═O)—O—], and those containing one copolymerizable carbon-carbonunsaturated bond in each molecule are preferred among others.

As the unsaturated carboxylic acids, there may be mentioned, forexample, aliphatic unsaturated carboxylic acids and the correspondingacid anhydrides. The aliphatic unsaturated carboxylic acids may bealiphatic unsaturated monocarboxylic acids or aliphatic unsaturatedpolycarboxylic acids containing two or more carboxyl groups.

As the aliphatic unsaturated monocarboxylic acids, there may bementioned, for example, aliphatic monocarboxylic acids containing 3 to20 carbon atoms such as propionic acid, acrylic acid, methacrylic acid,crotonic acid, and anhydrides thereof. As the aliphatic unsaturatedpolycarboxylic acids, there may be mentioned maleic acid, fumaric acid,mesaconic acid, citraconic acid [CAC], itaconic acid, aconitic acid,itaconic acid anhydride [IAH] and citraconic acid anhydride [CAH].

As the polymerization initiator in the method (2) mentioned above, theremay be mentioned diisopropyl peroxycarbonate, di-n-propylperoxydicarbonate, tert-butylperoxy isopropyl carbonate,bis(4-tert-butylcyclohexyl) peroxydicarbonate and di-2-ethylhexylperoxydicarbonate, among others.

The above-mentioned adhesive fluororesin preferably has a melting pointof not higher than 200° C., more preferably not higher than 180° C. fromthe viewpoint of the sealability of the laminated film obtained.

In the present specification, the above-mentioned melting point is thetemperature at the melting peak maximum value obtained by a measurementat a programming rate of 10° C./minute using a differential scanningcolorimeter (product of Seiko).

In the practice of the invention, the adhesive fluoropolymer film mayfurther have the form of a laminated film with a film other than theadhesive fluoropolymer film. In the practice of the invention, thelaminated film may be any one resulting from lamination of at least theadhesive fluoropolymer film and a film other than the adhesivefluoropolymer film, with the adhesive fluoropolymer film forming theoutermost layer of at least one side. The number of layers may be 2 ormore. From the viewpoint of conduction of heat to the contents, thatnumber is, but is not limited to, 2 to 5, preferably 2 or 3.

The thickness of the laminated film depends on the number of layers. Inthe case of a two-layer film consisting of a film other than theadhesive fluoropolymer film and the adhesive fluoropolymer film disposedon one side of the other film, the total film thickness is, but is notlimited to, about 20 to 200 μm, preferably 20 to 100 μm, particularlypreferably 20 to 60 μm, from the viewpoint of conduction of heat to thecontents.

The thickness of the adhesive fluororesin layer mentioned above ispreferably 5 to 100 μm, more preferably not thinner than 10 μm and notthicker than 50 μm.

In the practice of the invention, the laminated film, when formed by theabove-mentioned thermal lamination method, generally can have a bondstrength (x) of not lower than 200 N/m, preferably not lower than 300N/m, more preferably not lower than 400 N/m.

In the present specification, the above-mentioned bond strength (x) isthe strength required for 180-degree peeling on a Tensilon universaltesting machine at a speed of 25 mm/minute using 10-mm-wide specimensexcised from the laminated film and provided with margins for grippingat one end by peeling the adhesive fluororesin layer from the film otherthan the adhesive fluororesin film such as a PI film using a cutter.

The film other than the adhesive fluororesin film is not particularlyrestricted provided that it is not a film made of the adhesivefluoropolymer; a low-temperature resistant resin is preferred, however.

The low-temperature resistant resin is a resin excellent in shockresistance at temperatures not higher than about −40° C., preferably atabout −80° C. and lower temperatures. For example, mention may be madeof ultrahigh molecular weight polyethylene, polyimides,polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymers andethylene-vinyl acetate copolymers. From the viewpoint of conduction ofheat to the contents and of low-temperature resistance, polyimides,polytetrafluoroethylene and ethylene-tetrafluoroethylene copolymers arepreferred. More preferred are polyimides. From themoldability/processability viewpoint, the molecular weight of thelow-temperature resistant resin expressed in terms of number averagemolecular weight is, but is not limited to, about 1,000 to 1,000,000,preferably about 2,000 to 500,000, more preferably about 5,000 to300,000.

The shock resistance mentioned above is evaluated by the impact testbased on the free fall dart method (staircase method (JIS K 7124-1))using the resin film or resin sheet just after taking out of acryopreservation environment. Preferred as the resin excellent in shockresistance are those showing a 50% fracture energy (E50) of not lowerthan 0.1, preferably not lower than 0.2, more preferably not lower than1.0, in the above-mentioned staircase method (at the temperature ofliquid nitrogen).

The polyimide mentioned above may be any one comprising a heat-resistantpolymer having imide bonds in the main chain thereof; it includes, butis not limited to, nonthermoplastic polyimides having imide bonds alonein the main chain, wholly aromatic polyimides, organic solvent-solublepolyimides, polyetherimides and polyimideamides, among others.

The above-mentioned low-temperature resistant resin film includes, butis not limited to, those formed of a low-temperature resistant resin byhot melting under high temperature and high pressure conditions,extrusion or compression, or solvent casting.

As the method of lamination of the adhesive fluoropolymer film and thefilm other than the adhesive fluoropolymer film to give the laminatedfilm mentioned above, there may be mentioned the hot lamination method,hot compression method, high-frequency heating method and solventcasting method, among others. A preferred method is, but is not limitedto, the hot lamination method from the ease of production viewpoint. Theadhesive fluoropolymer film is firmly bonded to the film other than theadhesive fluoropolymer film, so that the adhesive fluoropolymer filmwill not peel off from the film other than the adhesive fluoropolymerfilm. From the safety production viewpoint, among others, thetemperature conditions in the above-mentioned hot lamination method are,but are not limited to, about 200 to 300° C., preferably about 200 to250° C.

In the practice of the invention, the laminated film can be formed bylaminating the film other than the adhesive fluoropolymer film, forexample the above-mentioned PI film, and the adhesive fluororesin.

The lamination of the PI film or a like film other than the adhesivefluoropolymer film and the adhesive fluororesin can be carried out bythe extrusion lamination method, for instance, and can also be carriedout by laminating the film other than the adhesive fluoropolymer film,for example a PI film, and the adhesive fluororesin by thermocompressionbonding, for instance.

The above-mentioned extrusion lamination may comprise, for example, anextrusion step (a) in which the adhesive fluororesin is melted andextruded onto the above-mentioned PI film or a like film other than theadhesive fluoropolymer film, the compression bonding step (b) in whichthe PI film or a like film other than the adhesive fluoropolymer filmand the adhesive fluororesin extruded are inserted between rolls forcompression bonding and the take-up step (c) in which the laminateproduced is taken up. Generally, the extrusion step (a), compressionbonding step (b) and take-up step (c) are carried out in that order.

The preferred extrusion temperature range in the above extrusion step(a) varies according to the kind of the PI film or a like film otherthan the adhesive fluoropolymer film and the kind of the adhesivefluororesin, the desired laminated film thickness and other factors.Generally, the range is preferably not lower than the melting point ofthe adhesive fluororesin used but lower than the decompositiontemperature of the same since laminated films high in interlaminar bondstrength are obtained in that range.

In the above extrusion step (a), the rate of extrusion of the moltenadhesive fluororesin onto the PI film or a like film other than theadhesive fluoropolymer film can be properly selected according to theadhesive fluororesin used and the composition and thickness, amongothers, of the PI film or a like film other than the adhesivefluoropolymer film. However, the step can be carried out within therange of 0.1 to 100 m/minute, for instance.

The above extrusion lamination, in particular the extrusion step (a), ispreferably carried out in an inert gas and/or the PI film or a like filmother than the adhesive fluoropolymer film is dried beforehand ordeprived of moisture by preheating so that the laminated film high ininterlaminar bond strength may be obtained.

In the practice of the invention, the extrusion lamination is consideredto be characterized in that the adhesiveness of the adhesive sitesoccurring in the adhesive fluororesin is displayed in the extrusionstep. When the extrusion lamination is carried out in an inert gasand/or the PI film or a like film other than the adhesive fluoropolymerfilm is dried in advance or deprived of moisture by preheating,supposedly, the adhesiveness can be fully displayed.

The operating conditions in the steps other than the extrusion step (a)in the above extrusion lamination can be properly selected in theconventional manner according to the kinds of the PI film or a like filmother than the adhesive fluoropolymer film and the adhesive fluororesin,the intended thickness of the laminated film and other factors.

When the lamination of the PI film or a like film other than theadhesive fluorine-containing film and the adhesive fluororesin is to becarried out in the manner of thermocompression, the lamination can becarried out generally by molding the adhesive fluororesin into a film bythe extrusion molding method known in the art, for instance, and layingthe adhesive fluororesin film obtained and the PI film or a like filmother than the adhesive fluoropolymer film one on the other andcompressing the assembly with heating.

The above-mentioned thermocompression is preferably carried out at atemperature of 120 to 300° C. Amore preferred lower limit to thattemperature is 140° C., and a more preferred upper limit thereto is 280°C.

The PI film or a like film other than the adhesive fluoropolymer filmmay be preheated in advance or dried beforehand prior to the laminationby thermocompression bonding, for instance.

When the respective layers are laminated by thermocompression, forinstance, the layers after lamination may be heated for aging so thatthe interlaminar bonding may be improved.

The heating for such aging is preferably carried out at 200 to 280° C.

The above-mentioned laminated film is shaped into a container orbag-like article by heat sealing. More specifically, two laminated filmsare placed one on the other so that the adhesive fluoropolymer filmscome into contact with each other and, then, heat sealing is carriedout. The capacity of the package is, but is not limited to, about 5 to500 ml, preferably about 10 to 300 ml, since the cryopreservationcontainer generally has a capacity of about 2 to 200 ml. In view of theseal strength between the laminated films, the heat seal width is, butis not limited to, about 2 to 20 mm, preferably about 5 to 15 mm. Alsofrom the viewpoint of the seal strength between the laminated films, theheat seal temperature is about 180 to 250° C., preferably about 200 to220° C. General-purpose fluororesin films cannot be sealed at such lowtemperatures as 180 to 250° C. Thus, the adhesive fluoropolymer filmaccording to the invention shows good sealability at low temperaturesand therefore is low in production process cost.

The package for a cryopreservation container according to the inventionis used for further packaging a cryopreservation container containingsuch a biological sample as erythrocytes, platelets, plasma or a likeblood component, bone marrow fluid, another body fluid or a cellsuspension. On that occasion, the air between the cryopreservationcontainer and the package can favorably be removed with ease by thepackaging method using an auxiliary device disclosed in Japanese KokaiPublication 2000-185716, for instance. The packaging method is notlimited thereto, however.

The package for a cryopreservation container according to the inventioncan be produced by shaping the laminated films into a container orbag-like article by the heat seal technique, for instance. Whenlaminated films having the outermost layer made of an adhesivefluoropolymer film at least one side are used as the above-mentionedlaminated films, the package for a cryopreservation container asobtained can be a container having the adhesive fluoropolymer film asthe outermost layer on at least one side thereof, preferably a containerhaving the adhesive fluoropolymer film as the outermost layer on atleast the inner side of the container.

The package for a cryopreservation container according to the inventioncan satisfactorily endure such very low temperatures as −80 to −196° C.In actually preserving such a blood component as erythrocytes, plateletsor plasma, bone marrow fluid or another body fluid or a cell suspension,gradual cooling is preferred so that such tissues may not be damaged.For example, there may be mentioned the method comprising once coolingthe whole package to about −80° C. in a deep freezer (refrigerator), forinstance, then transferring the same into liquid nitrogen forpreservation. The method of storage is not limited to such method,however. On the occasion of using the stored blood or cells, forinstance, the blood or cells can be thawed using means for warming, suchas a warm bath at 37 to 40° C. The method of thawing is not limited tosuch, however.

In storing a biological sample in the above-mentioned cryopreservationcontainer, a commercially available preserving fluid can be adequatelyused. In the case of storing cells, DMEM medium, RPMY 1640 medium, 199medium and phosphate buffer may be mentioned as preserving fluidstherefor. Preferably, about 0.5 to 2% by volume of albumin may be added.More preferably, dimethyl sulfoxide (DMSO) may be added as an agent forprotecting against freeze damage at a final concentration of about 5 to20% by volume. In the case of storing an organ, Euro-Collin's solutionand UW solution, among others, may be mentioned. Preferably, dimethylsulfoxide (DMSO) may be added as an agent for protecting against freezedamage at a final concentration of about 5 to 20% by volume. Theselection and preparation of such a preserving fluid can beappropriately made by the one skilled in the art, hence are notparticularly restricted.

As a method of freezing the package for a cryopreservation containeraccording to the invention, there may be mentioned the method comprisingfreezing the package used for further packaging the cryopreservationcontainer containing or storing a biological sample at 0° C. or below.Preferred as the method of freezing is the method comprising freezing at−80° C. or below. In the above method of freezing, the package ispreferably cooled gradually to a desired temperature for freezing sothat the biological sample may not be damaged. As such a method offreezing, there may be mentioned, for example, the method comprisingcooling the package once to about −80° C. in a deep freezer(refrigerator) and the immersing the same in liquid nitrogen. Thecryopreservation container may also contain such a preserving fluid asmentioned above according to need. The package is then generallyfreeze-preserved following freezing by the above method.

The package of the invention, which has the constitution describedhereinabove, will not be broken even at such a very low temperature asthe liquid nitrogen temperature (−196° C.) and will not show anydecrease in sealability at the sealed portion. Therefore, it will neverallow such a refrigerant as liquid nitrogen to enter the same and canprevent the contents from being contaminated or leaking out; thus, itshows good protective performance characteristics.

Furthermore, the above-mentioned package is tolerable in a lowtemperature range not so low as the above-mentioned very lowtemperatures provided that the temperature is lower than the meltingpoint of the adhesive fluororesin used and can show resistance to a verywide temperature range and will never undergo breakage or show decreasesin sealability at the sealed portion even upon rapid changes intemperature, for example when it is placed under ordinary temperatureconditions after placement at the above-mentioned very low temperatures.

While the mechanisms why the package of the invention produces suchexcellent effects as mentioned above are not clear, the followingcharacteristics presumably produce synergistic effects: (1) the PI isresistant to very low temperatures and can maintain the shape of themolded article even at very low temperatures as the liquid nitrogentemperature, (2) the package is excellent in the interlaminar adhesionbetween the PI film and the adhesive fluororesin layer, (3) the PI filmand the adhesive fluororesin layer can be bonded directly without usingany adhesive agent and, therefore, the problems encountered in using anadhesive agent, namely the problem of embrittlement and breakage of theadhesive layer at such very low temperatures as the liquid nitrogentemperature and the problem of outgas emission and substance elutionfrom the adhesive layer, can be avoided and (4) the package is formedfrom the laminated films obtained by lamination of the PI film and theadhesive fluororesin layer by mutual thermowelding of the adhesivefluororesin layers and therefore is excellent in the mutual adhesionbetween the adhesive fluororesin layers and has reliable sealability.

The package for a cryopreservation container according to the inventioncan be suitably used in packaging a cryopreservation container.

The cryopreservation container can be suitably used as acryopreservation container for a biological sample. As the biologicalsample that can be stored in the above cryopreservation container, theremay be mentioned, for example, human-derived biological samples,biological samples derived from animals other than humans or fromplants, viruses, microorganisms and like biological samples.

The above cryopreservation container is a container capable ofcontaining, in a tightly closed condition, such a biological sample as ablood component, cells, a tissue, an organ, viruses, bacteria, sperms,ova or fertilized ova, for instance. For example, mention may be made ofcommercially available polypropylene vials and the containers disclosedin Patent Documents 1 to 4. Preferred ones from the low-temperatureresistance viewpoint are, but are not limited to, freezing bags formedical use which are disclosed in Patent Document 4 and constituted oflaminated films consisting of an ultrahigh molecular weight polyethylenefilm and a thermoplastic resin film compatible with the ultrahighmolecular weight polyethylene.

As the blood component, there may be mentioned whole blood,erythrocytes, leukocytes, plasma, platelets and platelet rich plasma,among others. As the cells, there may be mentioned rare cells such ashematopoietic stem cells, ES cells, mesenchymal stem cells, mononuclearmarrow cells, spermatids and egg cells as well as common cells such asneurocytes, epithelial cells and fibroblasts. Further, as the vitaltissues, there may be mentioned various tissues and organs such astendons, nerves, ligaments, esophagi, tracheas, Langerhans islands,mucoepithelial tissues, keratoepithelial tissues, cultured cornealtissues and like membranous tissues as well as organs. such aspancreases, hearts, lungs, livers and kidneys. As the viruses, there maybe mentioned hepatitis B virus, hepatitis C virus, coronavirus andmosaic virus, among others. As the bacteria, there may be mentionedMycobacterium tuberculosis, Haemophilus influenzae, Escherichia coli,Staphylococcus aureus, hemolytic streptococci and Klebsiella pneumoniae,among others. Further, sperms, ova and fertilized ova may be mentionedin relation to the field of infertility treatments, for instance. Theseblood or blood components, cells including rare cells and other vitaltissues to be stored are selected at the workers' discretion accordingto the intended purpose, hence are not particularly restricted.

As the vital tissues, there may further be mentioned, for example,living organism-derived body fluids (blood, cerebrospinal fluid, lymph,etc.) and components thereof (erythrocytes, leukocytes, platelets,plasmas, sera, etc.), living organism-derived tissues (blood vessels,corneas, menisci, cerebral tissues, skins, subcutaneous tissues,epithelial tissues, osseous tissues, muscular tissues, etc.), organs(eyes, lungs, kidneys, hearts, livers, pancreases, spleens, digestivetracts, bladders, ovaries, testicles, etc.), various cells(hematopoietic stem cells such as cord blood- or peripheralblood-derived hematopoietic stem cells, marrow cells, hepatocytes,splenocytes, brain cells and other various organ cells, neurocytes,sperms, egg cells, fertilized ova, embryonic stem cells (ES cells),cancer cells for research and therapeutic purposes, cultured cells, stemcells, germ cells, etc.) and so forth.

As the biological samples, there may be mentioned human vital tissues,inheritance-related substances and, further, vital tissues andinheritance-related substances derived from animals including smallanimals such as small experimental animals; microorganisms, bacteria,and inheritance-related substances derived therefrom; and so forth.These are used in the research field, for instance.

As the biological samples, there may further be mentioned vital tissuesand inheritance-related substances derived from domestic animals andanimals and those used in the fields of researches, cultures,cultivations, horticulture and agriculture.

As the biological samples, there may also be mentioned plant seeds,pollens, cultured cells, shoot apex cells and inheritance-relatedsubstances.

As the biological samples, there may further be mentioned vital tissuesand inheritance-related substances derived from marine algae, fish andthe like. These are used, for example, in researches in the field offishery sciences.

As the inheritance-related substances, there may be mentioned DNAS,hosts, vectors and so forth.

The biological samples mentioned above can be used for medical purposes;in research and development in the fields of agriculture, animalhusbandry, forestry, fishery, horticulture and so forth; in thetreatment of diseases, infertility treatment and breeding of animals inthe pet industry and animal industry and for the cloning technology, forinstance.

Thus, the cryopreservation container mentioned above can be used invarious fields such as medical treatment; researches; animal husbandry,horticulture and agriculture; and fishery, and the package for suchcryopreservation container according to the invention can also be usedin various fields.

EXAMPLES

The following examples illustrate the present invention in detail. Theseexamples are, however, by no means limitative of the scope of theinvention.

Examples 1 to 4 Production of Packages for Cryopreservation Containers

A two- or three-layer film was produced by the hot lamination methodusing a polyimide film and one or two films made of a ternary systemrandom copolymer produced from tetrafluoroethylene, perfluoro(vinylpropyl ether) andperfluoro(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol) (hereinafter referred to as “inner layer fluororesin film”and “outer layer fluororesin film”) as applied to one side or both sidesof the polyimide film. Sheets with a size of 100×95 mm were cut fromeach film and packages (25 ml in capacity) for cryopreservationcontainers were produced by laying one of two sheets on top of the otherso that the inner layer fluororesin films came into contact with eachother and heat-sealing 2-mm-wide margins. The polyimide film thicknessand inner layer fluororesin film thickness data are shown in Table 1.

The copolymer composition of the ternary system random copolymer filmwas such that the ratio ofperfluoro(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol) monomer units to tetrafluoroethylene monomer units plusperfluoro (vinyl propyl ether) monomer units was 1:99. The copolymercomposition was determined by ¹⁹F-NMR.

Comparative Example 1

Packages made of a perfluoroethylene-propylene copolymer were used aspackages for cryopreservation containers for comparison.

Reference Example 1 Cryopreservation Containers to be Packaged inPackages

Cryopreservation containers made of a laminated film produced bylaminating an ultrahigh-molecular-weight polyethylene film and twolow-molecular-weight polyethylene films on both sides of the former wereused.

Synthesis Example 1 Synthesis of an Adhesive Fluororesin

A 820-liter glass-lined autoclave was charged with 200 L of pure water,the system inside was thoroughly purged with nitrogen gas and then thenitrogen was evacuated therefrom. The autoclave was charged with 113 kgof 1-fluoro-1,1-dichloroethane, 95 kg of hexafluoropropylene and 85 g ofcyclohexane. Then, 292 g of perfluoro (1,1,5-trihydro-1-pentene)[CH₂═CF(CF₂)₃H] was fed to the autoclave under pressure using nitrogengas, and the vessel inside temperature was maintained at 35° C. and therate of stirring at 200 rpm. Further, tetrafluoroethylene was fed to theautoclave until arrival of the pressure at 7.25 kg/cm²G, followed byfeeding of ethylene until arrival of the pressure at 8 kg/cm²G.

Then, the polymerization was started by feeding 1.9 kg of a 50% (bymass) solution of di-n-propyl peroxydicarbonate in methanol. Sinceotherwise the vessel inside pressure fell with the progress of thepolymerization, a tetrafluoroethylene/ethylene/hexafluoropropylene mixedgas (mole ratio=39.2:43.6:17.3) was additionally fed under pressure and,while maintaining the polymerization pressure at 8 kg/cm²G in thatmanner, the polymerization was continued and, during the polymerization,1100 g of CH₂═CF(CF₂)₃H, divided in 20 portions, was charged using amicropump. The polymerization was carried out for a total of 32 hours.After completion of the polymerization, the contents were recovered andwashed with water to give 95 kg of a powdery adhesive fluororesin.

The adhesive fluororesin obtained was subjected to the followingmeasurements.

(1) Monomer Units

¹⁹F-NMR analysis was carried out and determinations were made.

(2) Number of Carbonate Groups

A film with a thickness of 0.05 to 0.2 mm was prepared by compressionmolding of the adhesive fluororesin powder at room temperature. The filmobtained was subjected to infrared absorption spectrometry, and theabsorbance of the peak [1809 cm⁻¹ (ν_(c═O))] assignable to the carbonylgroup in the carbonate group [—OC(═O)—O—] was measured. The number ofcarbonate groups per 1×10⁶ main chain carbon atoms was calculated basedon the measured value obtained according to the formula given below.

N=500AW/εdf

A: Absorbance at the above-mentioned ν_(C═O)

ε: Molar extinction coefficient at the above ν_(C═O)[1.cm⁻¹.mol⁻¹]

(The value ε=170 was employed based on the results with modelcompounds.)

W: Composition average molecular weight calculated based on the monomercomposition

d: Film density [g/cm³]

f: Film thickness [mm] measured using a micrometer.

The above infrared absorption spectrometry was carried out by making 40scans on Perkin-Elmer FTIR spectrometer 1760×(product of Perkin-Elmer).The analysis of the absorbance of ν_(c═O) was carried out usingPerkin-Elmer Spectrum for Windows (registered trademark) Ver. 1.4Csoftware.

(3) Melting Point

The measurement was carried out at a programming rate of 10° C./minuteusing a differential scanning calorimeter (product of Seiko) and thetemperature at the maximum of the melting peak obtained was regarded asthe melting point.

The adhesive fluororesin obtained had a monomer unit composition ofTFE/Et/HFP/CH₂═CF(CF₂)₃H=38.9/45.9/14.8/0.4, the number of carbonategroups was 411 per 1×10⁶ main chain carbon atoms and the melting pointthereof was 171.8° C.

Example 5

(1) The adhesive fluororesin obtained in the synthesis example wasmolded into an adhesive fluororesin film (thickness: 25 μm) through a Tdie mounted on a single screw extruder with a cylinder diameter of 90 mmunder the conditions of a cylinder temperature of 170 to 230° C., a dietemperature of 230° C. and a screw speed of 10 rpm. The adhesivefluororesin film obtained and a polyimide film (product name: Kapton100H, product of Du Pont Toray, thickness: 25 μm) were laminated using ahot roll at a temperature of 250° C. to give a laminated film (length 20m×width 200 mm×total thickness 50 μm; hereinafter referred to also as“continuous film”). Rectangular specimens, 100 mm in the lengthwisedirection and 10 mm in the transverse direction, were cut out from thelaminated film obtained (fluororesin layer thickness: 25 Ξm, polyimidelayer thickness: 25 μm). Each specimen was provided with margins forgripping at one end by peeling the adhesive fluororesin layer from thepolyimide layer using a cutter and subjected to 180-degree peeling on aTensilon universal testing machine (product of Orientec) at a speed of25 mm/minute. The bond strength of the laminated film was 400 N/m.(2) Then, two 12-cm-square laminated film sheets were excised from theabove-mentioned continuous sheet and placed one on top of the other withthe adhesive fluororesin layers inside, and three sides werefusion-bonded by heating at 210° C. for 5 seconds using a heat sealer.The seal width (bonding part width) was 1 cm. Thus, a package (capacity:25 ml) for a cryopreservation container was formed. The thickness of thepolyimide film and the thickness of the adhesive fluororesin film (innerlayer fluororesin film) are shown in Table 1.

TABLE 1 Inner layer fluororesin film Polyimide film Example 1 25 μm 25μm Example 2 50 μm 25 μm Example 3 25 μm 50 μm Example 4 50 μm 50 μmExample 5 25 μm 25 μm

Experimental Example 1 Freezing Test

A 10% (by volume) aqueous solution of DMSO (in about 25-ml portions) waspacked in cryopreservation containers described in Reference Example 1.These cryopreservation containers were packaged with the packages ofExamples 1 to 5 and Comparative Example 1, respectively, and were put inaluminum cases, respectively. The cases were allowed to stand in a deepfreezer (refrigerator) at −80° C. for 4 hours for freezing the contents.After this freezing treatment, the packages with the respectivecryopreservation containers in the aluminum cases were transferred intoliquid nitrogen and stored for 1 week. The stored packages with therespective cryopreservation containers were taken out of the aluminumcases and placed in a warm bath at 37 to 40° C. for thawing, and eachpackage was observed by the eye as to whether there was any damage orliquid nitrogen intrusion or some other trouble.

The results of this experiment are shown in Table 2. In ComparativeExample 1, the percent breakage was 2%, whereas the packages forcryopreservation containers according to the invention all showed nobreakage at all in spite of the great number of tests, namely 100packages in each example.

TABLE 2 Number of damaged packages/ number of packages tested Example 10/100 Example 2 0/100 Example 3 0/100 Example 4 0/100 Example 5 0/100Comparative 2/100 Example 1

Experimental Example 2 Freezing Test

A cell suspension was prepared by suspending MOLT-4 cells (obtained fromRIKEN) in RPMI 1640 medium (product of Invitrogen) to a concentration ofabout 1.0×10⁷ cells/ml. This cell suspension was packed, in about 25-mlportions, in cryopreservation containers described in ReferenceExample 1. These cryopreservation containers were packaged with thepackages of Example 5 and Comparative Example 1, respectively, and wereput in aluminum cases, respectively. The cases were allowed to stand ina deep freezer (refrigerator) at −80° C. for 4 hours for freezing thecontents. After this freezing treatment, the packages with therespective cryopreservation containers in the aluminum cases weretransferred into liquid nitrogen and stored for 1 week. The storedpackages with the respective cryopreservation containers were taken outof the aluminum cases and placed in a warm bath at 37 to 40° C. forthawing, and each package was observed by the eye as to whether therewas any damage or liquid nitrogen intrusion or some other trouble. Ineach example, 10 tests were performed.

As a result, one cryopreservation container package was found damaged inComparative Example 1 whereas the 10 cryopreservation container packagesaccording to the invention showed no damage at all.

INDUSTRIAL APPLICABILITY

The package for a cryopreservation container according to the inventionmakes it possible to store blood, rare cells and vital tissues in a verylow temperature environment without any damage to the package/container.Since it has a relatively thin film thickness, it will not reduce theconduction of heat to the contents of the cryopreservation container inthe package. Further, the sealing strength resulting from heat sealingafter placing a cryopreservation container in the packages is very goodand, therefore, liquid nitrogen can be inhibited from entering theinside and thus contamination with bacteria, viruses or the likecontained in liquid nitrogen can be avoided and the package can beprevented from being broken by expansion of intruder liquid nitrogen onthe occasion of thawing.

1. A package for a cryopreservation container comprising at least anadhesive fluoropolymer film.
 2. The package for a cryopreservationcontainer according to claim 1, wherein the adhesive fluoropolymer filmis made of an adhesive fluoropolymer containing at least one adhesivesite.
 3. The package for a cryopreservation container according to claim2, wherein the at least one adhesive site is selected from the groupconsisting of carbon-carbon double bond, carbonyl group [—C(═O)],carbonyl group-containing groups or bonds, hydroxyl group, cyano group,sulfonic acid group and epoxy group.
 4. The package for acryopreservation container according to claim 3, wherein the adhesivefluoropolymer contains at least one reactive functional group as theadhesive site and is a copolymer obtained by copolymerizing thefollowing monomers (A) and (B): (A) A fluorinated monomer containing noreactive functional group; (B) A fluorinated monomer containing the atleast one reactive functional group.
 5. The package for acryopreservation container according to claim 4, wherein the fluorinatedmonomer containing no reactive functional group is represented by theformula (1) given below:

(wherein X¹ and X² each is hydrogen atom or halogen atom and Y ishydrogen atom, fluorine atom, a fluorinated alkyl group containing 1 to5 carbon atoms or a fluorinated oxyalkyl group containing 1 to 5 carbonatoms).
 6. The package for a cryopreservation container according toclaim 5, wherein the fluorinated monomer containing no reactivefunctional group comprises at least one monomer selected from the groupconsisting of tetrafluoroethylene, vinylidene fluoride,1,2-difluorochloroethylene, hexafluoropropylene, perfluoro(vinyl methylether) and perfluoro(vinyl propyl ether).
 7. The package for acryopreservation container according to claim 4, wherein the fluorinatedmonomer containing the at least one reactive functional group isrepresented by the formula (2) given below:

(wherein X¹ and X² each is hydrogen atom or halogen atom, Z is hydroxylgroup, carboxyl group, cyano group, sulfonic acid group or epoxy groupand R_(f) is a fluorinated alkylene group containing 1 to 40 carbonatoms, a fluorinated oxyalkylene group containing 1 to 40 carbon atomsor a fluorinated alkylene group containing 1 to 40 carbon atoms and atleast one ether bond).
 8. The package for a cryopreservation containeraccording to claim 4, wherein the adhesive fluoropolymer is representedby the formula (3) given below:

(wherein X¹ and X² each is hydrogen atom or halogen atom, Y¹ and Y² eachis hydrogen atom, fluorine atom, a fluorinated alkyl group containing 1to 5 carbon atoms or a fluorinated alkoxy group containing 1 to 5 carbonatoms, Z is hydroxyl group, carboxyl group, cyano group, sulfonic acidgroup or epoxy group, R_(f) is a fluorinated alkylene group containing 1to 40 carbon atoms, a fluorinated oxyalkylene group containing 1 to 40carbon atoms or a fluorinated alkylene group containing 1 to 40 carbonatoms and at least one ether bond and the ratio (1+m)/n is 2 to 2000).9. The package for a cryopreservation container according to claim 3,wherein the adhesive fluoropolymer comprises a fluorinatedmonomer-derived fluorinated monomer unit and a nonfluorinatedmonomer-derived nonfluorinated monomer unit.
 10. The package for acryopreservation container according to claim 9, wherein the fluorinatedmonomer is tetrafluoroethylene and the nonfluorinated monomer isethylene.
 11. The package for a cryopreservation container according toclaim 1 comprising: the adhesive fluoropolymer film on at least oneoutermost layer and a film other than said adhesive fluoropolymer film.12. The package for a cryopreservation container according to claim 11,wherein the film other than the adhesive fluoropolymer film is alow-temperature resistant resin film.
 13. The package for acryopreservation container according to claim 12, wherein thelow-temperature resistant resin comprises at least one resin selectedfrom the group consisting of ultrahigh molecular weight polyethylene,polyimides, polytetrafluoroethylene, ethylene-tetrafluoroethylenecopolymers and ethylene-vinyl acetate copolymers.
 14. The package for acryopreservation container according to claim 13, wherein thelow-temperature resistant resin is a polyimide.
 15. A method ofproducing a package for a cryopreservation container comprising shapingan adhesive fluoropolymer film into a bag-like article by heat sealing.16. The method of producing a package for a cryopreservation containeraccording to claim 15, comprising shaping a laminated film comprisingthe adhesive fluoropolymer film on at least one outermost layer and afilm other than said adhesive fluoropolymer film, into a bag-likearticle by heat sealing.